This invention relates to a power supply arrangement for providing auxiliary power to the electrical system of a building, such as from a standby generator or the like.
Portable generators are used in certain situations to supply electrical power to residential and commercial load circuits during a utility power outage. A system for interconnecting the generator with the load center of a building typically includes a power inlet box having a receptacle for receiving a plug extending from the generator.
The power inlet box is typically mounted to the exterior of a building, and is adapted for connection to a transfer switching mechanism which establishes an electrical path between the generator and the load center. The transfer switching mechanism typically includes a series of switches and circuit breakers, which are operable to supply power to certain selected circuits of the load center. The circuits of the transfer switching mechanism are wired to selected circuits of the load center, through wiring housed within a conduit extending between the transfer switching mechanism and the load center.
A typical transfer switching mechanism includes a housing provided with a power input receptacle. The remote power inlet box is wired to a power cord connected to a junction box, and the power cord is engageable with the power input receptacle of the transfer switching mechanism so as to provide power to the transfer switching mechanism from the generator. An alternative arrangement is illustrated in Flegel U.S. Pat. No. 5,895,981 issued Apr. 20, 1999, the disclosure of which is hereby incorporated by reference. In the '981 patent, the transfer switching mechanism includes a terminal compartment within which a set of terminals is located. The terminals are wired to the switches of the transfer switching mechanism. A set of power input wires extends from the power inlet box, and into the terminal compartment of the transfer switching mechanism. The ends of the power input wires are connected to the terminals, to establish a direct, non-plug type connection between the power inlet box and the transfer switching mechanism.
U.S. Pat. No. 6,414,240 issued to Flegel on Jul. 2, 2002 describes a power transfer switching mechanism that includes a cabinet defining an internal cavity within which a series of switches are mounted. One or more lead wires are connected to the switches, and define ends which extend into a compartment. The compartment is accessible through an opening associated with the cabinet, and a cover is selectively positionable over the opening to provide or prevent access to the compartment. With the cover removed, the lead wires can be connected to power input wires in a conventional manner, e.g., using wire-to-wire connectors, and the wires and the connectors may then be placed within the compartment and concealed by attaching the cover to the cabinet.
The present invention provides a power transfer switching mechanism that improves upon the advancements to the art provided by the '240 patent to Flegel. More particularly, in accordance with one embodiment of the present invention, a power transfer switching mechanism includes a housing having a base defining an internal cavity that may be segmented into first and second compartments, which may be in the form of upper and lower compartments, by an intermediate and removable wall member. The base may be generally defined by a back wall and a pair of sidewalls extending outwardly from the back wall, and which may be integrally formed with the back wall. A mating engagement arrangement is interposed between the base and the intermediate wall member. The mating engagement arrangement may be in the form of a channel formed along the inner surface of the back wall and along facing inner surfaces of the sidewalls. The intermediate wall member may be configured for engagement within the channel, and functions to partition the base into the first and second sections, which may be an upper section and a lower section. In one embodiment, a first (or upper) panel engages portions of the sidewalls and the intermediate wall member, and is configured to fit over the first section to define the first or upper compartment. In a similar fashion, a second (or lower) panel engages portions of the sidewalls and the intermediate wall member, and is configured to fit over the second or lower section to define the second or lower compartment. The panels may have curved wall portions that define a top and bottom of the housing when engaged with the base. The curved wall portions assist with moisture runoff when the switching mechanism is mounted outdoors. Alternatively, the housing may be formed without the intermediate wall member and with a single front panel.
A plurality of electrical components associated with the feeding of standby (generator) electrical power to the electrical system of the building is mounted to a panel that is secured to the base. In an embodiment in which there is more than one panel, the electrical components are preferably mounted to a single one of the panels, e.g., an upper panel. In one implementation, the electrical components include switches, circuit breakers, power meters, and/or a light that provides surface illumination of the panel. In a representative method of assembling the power transfer switching mechanism, one or more of the electrical components are mounted to the panel to form a subassembly that is mounted as a single unit or body to the base. Mounting the electrical components to the upper panel, for example, as opposed to the base gives an assembler more room when interconnecting the electrical components to lead wires, and also allows the components to be quickly and easily secured to the panel at a location away from the base, e.g. with the panel secured in an assembly fixture. When the panel is engaged with the base, the lead wires have ends which extend into and are located within the lower compartment. The ends of the lead wires are adapted for engagement with a power input interconnected with the auxiliary power source, such that the lead wires establish an electrical path between the power input and the electrical components.
The power input may be in the form of a series of power input wires which extend from a remote power inlet box, which includes a power input receptacle for receiving a plug-type connector extending from the auxiliary power source, such as a portable generator. In this embodiment, the power input wires are connected to the ends of the lead wires, such as by twist-on connectors. Once the appropriate connections have been made, the wire ends and connectors are placed within the lower compartment of the power transfer device housing. The lower panel is secured in place over the lower compartment, so as to enclose the lower compartment within which the wire ends and the connectors are located.
A cover may be pivotally mounted to the upper panel and is movable between raised and lowered positions to selectively allow and prevent access to the series of switches. The cover is sized to fit over the upper and the lower panels and thus advantageously reduces the ingress of precipitation or other moisture onto the upper and lower panels and generally within the upper and lower compartments. The use of the cover is particularly beneficial with outdoor mountings of the power transfer switching mechanism. The cover however may be removed in a tool-free manner as may be desired for indoor mountings.
The cover and the base are preferably fabricated from a corrosion-resistant material, such as a thermoplastic material, for outdoor applications of the power transfer switching mechanism. The upper and lower panels engage the base in a clamshell like manner to provide a generally weather-tight engagement of the upper and lower panels to the base. Furthermore, the construction of the upper and lower panels and the base, and the manner in which these components fit together, enables the power transfer switching mechanism to be assembled quickly and efficiently.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.